The gift of runoff in a wet season

One recent evening, a friend and I walked along a mountain creek in central Colorado that only a few hours before had been covered with snow. Boulders once visible had been replaced by froth and waves, and the water velocity was so great that the middle of the creek was a foot higher than its edges.

Mountain water hurrying downstream is as pleasing a sound as I know. This year has kept the music flowing, the creeks and rivers of the Rockies coursing bank to bank even into mid-July, weeks after the happy roar has usually subsided.

From a bridge in Vail, I dropped a stick into Gore Creek and watched it bounce along the pinball of rapids at a speed that my friend, a kayaker, estimated around 6 mph. In a car, that may feel painfully slow, but for water speed that's pretty fast. My friend calculated his chances on a kayak descent. I considered other equations, such as where this water will end up. Forty miles downstream, Gore Creek flows into the Colorado River, and normally it would end up in Mexico and then the Pacific Ocean. But normal long ago was redefined in the Colorado River Basin.

The Colorado River in its namesake state often carries little water because much of the spring surplus gets detained by giant dams, with some of it diverted to Denver and other cities as well as to farms spread out onto the Great Plains. Deprived of natural, flushing-out flows, these headwater creeks get clogged by sediments, depriving mayflies and other bugs of their habitat, and hence depriving fish of the prey they need.

In Mexico, the story is the same. The Colorado River has not reached the Pacific Ocean with any regularity since the 1960s. As Philip Fradkin observed in a book decades ago, it has been so tamed and transformed that it is basically "A River No More."

In recent years, the major story in the American Southwest has been about drought and ominously early runoff. For a time, it looked as if Lake Powell, that great splish-splash of desert amusement in Utah, might even shrink into a dead pool, with too little water in it to produce electricity. Lake Mead near Las Vegas, when I visited last December, was at its lowest level since 1938, shortly after Hoover Dam was constructed. Las Vegas, which draws most of its water from Lake Mead, is boring a new $700 million tunnel. In case things get really bad, the tunnel will enter the bottom of the reservoir to draw water. Now, that's hedging your bets.

This summer, it all seems less dire. A La Niña winter left Arizona and New Mexico kindle-dry, ripe for fires, but snowpacks in much of Colorado, Utah and New Mexico crowded the record books. Spring glanced over its shoulder at the lingering winter, augmenting the deep already snows and delaying runoff. That runoff is now filling headwater reservoirs and downstream, partially eclipsing the bathtub rings in the two giant buckets in the desert, Powell and Mead. Boat ramps abandoned in recent years for lack of water are suddenly once again functional.

Taking this year in isolation, some people make the argument that all this watery plenty disproves global warming. Unfortunately, that's a foolish argument. The scientific evidence still stacks up strongly in favor of shorter winters over the long term. And almost certainly, summers will be far hotter. The U.S. Bureau of Reclamation earlier this year concluded the Colorado River could carry an average of 9 percent less water annually in coming decades.

More intense heat also means more evaporation. Already, Lake Powell loses six and a half feet of its surface each year. Greater heat also means thirstier fields of corn, alfalfa and cotton. Agriculture uses between 50 to 90 percent of the water in the states of the Colorado River Basin, even as summer lawn irrigation uses the lion's share of municipal water.

Some 30 million people now depend in part or whole on the Colorado River, its water exported ingeniously outside the basin to Cheyenne, Salt Lake City, Albuquerque and, of course, Los Angeles and San Diego. Choices still must be made: Agriculture, people and the environment all need water. Of necessity, there must be new models for sharing, continued calculations of the various values of water, financial and otherwise.

But this year, those hard conversations seem less pressing. The rivers are swollen, the reservoirs filling, the gardens growing. For a while, we can echo the writer Wallace Stegner and revel in the wonderful sound of mountain water.

Allen Best is a contributor to Writers on the Range, a service of High Country News (hcn.org). He writes about the environment from the Denver area.